When four U.S. secret agents and ten Russian moles were freed and handed over to their respective countries of employment at the Vienna Airport on July 10, the spies on Beijing’s payroll would no doubt have been envious. Beijing has shown over the years that it does not come to the rescue when its own spies are caught.

The Russian spy story has excited the imagination of Americans with its Cold-War-like plot and Hollywood-esque details (like the Russian femme fatale who lives a double life). But what many people don’t realize is that this new breed of Russian spies are caricatures of their predecessors. Their skills are questionable, and they need to prove the value of their information and their own worth to their employer.

Their capable and poised Chinese counterparts, on the other hand, pose a sinister threat to America’s welfare.

Congressman J. Randy Forbes expressed his concerns over the “deliberate and methodical methods of espionage practiced by trained spies, students, and civilians” in his response to the arrest of four Chinese spies in 2008. “China poses the number one espionage threat to the United States,” the Congressman said. “The effects of that threat are real and dangerous to the interests of the United States.”

The FBI has estimated that up to 3,200 Chinese front companies are operating in the United States, gathering secret information about the U.S. government and American companies. Only some of them have been exposed. The U.S. Justice Department has convicted 44 individuals in 26 cases since March 2008; almost all of them are now serving time in federal prisons, according to the Washington Post.

The most famous and dramatic case may be that of Larry Wu Tai Chin, who served the CIA for 30 years until 1985, when a defecting Chinese official reported him as one who had been selling classified documents to China since 1952.

While awaiting sentencing, Chin called upon China to help rescue him, by handing over the then jailed democracy activist Wei Jingsheng. But Beijing, who Chin had served for 33 years, publicly denied any connection.

"Chin Wu Tai’s case is fabricated by America’s anti-China forces. The Chinese government is peace-loving and has never sent any spy to any country," said China’s spokesman Li Zhaoxing at a press conference.

The press conference took place not long after Chin’s wife went to Beijing to appeal to communist party leader Deng Xiaoping for help. “The Chinese government will not tolerate this anti-China incident, and has nothing to do with this self-claimed Chinese spy, Mr. Chin Wu Tai,” was the terse assertion.

In fact, only later did it come to light that Chin's service had indeed proved invaluable to Beijing's cause. Without his aid, Korean war armistice negotiations would not have been delayed for a year, and a vast number of lives would have thus been spared.

Shortly after his sentence of life imprisonment was handed down on Feb. 22, 1986, Chin, one of China’s most famous spies, was found dead. It appeared that he had snuffed out his own life with a plastic bag tied around his neck with a shoelace.

The real cause of Chin’s death has remained controversial, because taking one’s life in such a way is apparently no easy task.

In her book Death of My Husband: Larry Wu-Tai Chin, Chin’s wife Cathy Chin said it was very likely that Beijing agents had assassinated her husband.

Since then, the U.S. has apprehended many Chinese spies. FBI agent Katrina Leung was found to be a double agent in 2003, and had been in sexual relationships with at least two FBI agents. Chi Mak was sentenced to 15 years’ imprisonment in 2007, for exporting sensitive defense technology to China. Taiwan-born U.S. businessman Tai Shen Kuo was sentenced to 15 years in prison in 2008, for selling military secrets to China. Earlier this year, China-born Boeing engineer Dongfan "Greg" Chung was sentenced to more than 15 years in prison, for stealing sensitive information on the U.S. space program.

Beijing has staunchly denied involvement with any of the espionage cases, or connections with the convicted individuals. Consequently these spies have been left rotting in jail, if not dying under suspicious circumstances. This is in sharp contrast to the painstaking endeavors of almost all other countries to rescue their own spies, including the former Soviet Union. The rescued spies often enjoy a hero’s welcome upon return to their home countries.

The U.S. is far from the only country that China’s huge spy network has stolen political, military and industrial secrets from. Two Chinese defectors said in 2005 that the Chinese government had more than 1,000 spies and informants in Canada, while Japan’s National Public Safety Commission has identified a female Chinese spy who controlled 30,000 Chinese spies in Japan, as reported by Japan’s popular magazine, Shukan Post. Back in 2005, Chinese spies had cost Canada one billion dollars every month from industrial espionage, according to Prime Minister of Canada Stephen Harper.

Revelations about rampant espionage from China continue to unravel, with the governments of many countries becoming more wary than ever of Chinese spies. As more Chinese spies continue to be rooted out, the world will hear more of Beijing’s cast-in-stone denials, and witness more tears, remorse, and fear from its abandoned ‘assets.’

It’s a good thing that today plastic bags and shoe laces are not as readily available in American prisons.

Cao Changqing is a well-known political commentator, originally from mainland China, currently residing in the U.S.